This invention relates to a carbon yarn and more particularly to a method for reducing broken fibers on the surface of the carbon fiber yarn bundle.
Generally, the conventional commercial process for producing a mesophase pitch derived carbon yarn includes the steps of forming a plurality of mesophase pitch fibers to define a mesophase pitch yarn, thermosetting the mesophase pitch yarn to produce a thermoset yarn, and thereafter subjecting the thermoset yarn to a thread-line heat treatment in an inert atmosphere to pyrolyze and carbonize the thermoset yarn and produce the carbon yarn. U.S. Pat. No. 4,351,816 to Schulz describes a known process for producing carbon yarn and recites the problems associated with surface defects such as broken fibers and discloses a method for providing a carbon yarn substantially free of frays or broken fibers.